1. Field of Invention
The present invention relates to a tool and, more particularly, to a tool joint for connecting a handle with various bits.
2. Related Prior Art
In Taiwanese Patent M2403 11, a conventional screwdriver is disclosed. This conventional screwdriver includes a handle 1, a bit 3 inserted in the handle 1, a locking device 2 installed in the handle 1 in order to lock the bit 3 and a controlling device 4 installed on the handle 1 in order to control the locking device 2. The locking device 2 includes a socket 22 with an axial passage 221 for receiving the bit 3 and two apertures communicated with the axial passage 221. An annular flange is formed on the socket 22. Two balls 222 are put in the apertures of the socket 22. A ring 21 is installed on the socket 22. The ring includes a tapered internal side 211 for pushing the balls 222. A spring 24 is installed on the socket 22. A C-clip is engaged with the socket 22 opposite to the annular flange. Thus, the spring 24 is compressed between the C-clip and the ring 21. Thus, the tapered internal side of the ring 21 pushes the balls 222 into contact with the bit 3. The controlling device 4 includes two wedges 42 provided between the ring 21 and the annular flange of the socket 22. Each wedge 42 is connected with a button 41. When the buttons 41 are pushed, the wedges 42 push the ring 21 from the annular flange of the socket 22. Thus, the tapered internal side of the ring 21 allows the balls 22 to leave the bit 3. However, a few problems are encountered in use of this conventional screwdriver. Firstly, short bits cannot be used, because the locking device 2 is located deep into the handle 1. Secondly, the bit 3 might accidentally be released, because the buttons 42 are pushed by mistake since the buttons 42 are located-close to an area of the handle 1 that is held.
The present invention is therefore intended to obviate or at least alleviate the problems encountered in prior art.